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Groups > linux.kernel > #1186795
| From | "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [RFC PATCH v2] memory-barriers: remove smp_mb__after_unlock_lock() |
| Date | 2015-07-17 14:50 +0200 |
| Message-ID | <pNdft-5HQ-23@gated-at.bofh.it> (permalink) |
| References | (5 earlier) <pMJKq-5my-9@gated-at.bofh.it> <pMT73-22W-15@gated-at.bofh.it> <pN0ie-3Os-21@gated-at.bofh.it> <pNahz-1uy-13@gated-at.bofh.it> <pNaUh-2ta-15@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Fri, Jul 17, 2015 at 12:15:35PM +0200, Peter Zijlstra wrote:
> On Fri, Jul 17, 2015 at 10:32:21AM +0100, Will Deacon wrote:
> > @@ -158,9 +140,7 @@ void arch_spin_lock_flags(arch_spinlock_t *lock, unsigned long flags)
> >
> > static inline void arch_spin_unlock(arch_spinlock_t *lock)
> > {
> > - SYNC_IO;
> > - __asm__ __volatile__("# arch_spin_unlock\n\t"
> > - PPC_RELEASE_BARRIER: : :"memory");
> > + smp_mb();
> > lock->slock = 0;
> > }
>
> Should we then also make smp_store_release() use sync instead of lwsync
> to keep it consistent?
Unless smp_store_release() needs to interact with MMIO accesses, it
should still be able to be lwsync. This means that unlock-lock is a full
barrier, but relase-acquire is not necessarily, which should be just fine.
Thanx, Paul
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[RFC PATCH v2] memory-barriers: remove smp_mb__after_unlock_lock() Will Deacon <will.deacon@arm.com> - 2015-07-13 14:20 +0200
Re: [RFC PATCH v2] memory-barriers: remove smp_mb__after_unlock_lock() Peter Zijlstra <peterz@infradead.org> - 2015-07-14 10:40 +0200
Re: [RFC PATCH v2] memory-barriers: remove smp_mb__after_unlock_lock() Will Deacon <will.deacon@arm.com> - 2015-07-14 12:10 +0200
Re: [RFC PATCH v2] memory-barriers: remove smp_mb__after_unlock_lock() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-07-14 21:40 +0200
Re: [RFC PATCH v2] memory-barriers: remove smp_mb__after_unlock_lock() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-07-15 03:40 +0200
Re: [RFC PATCH v2] memory-barriers: remove smp_mb__after_unlock_lock() Will Deacon <will.deacon@arm.com> - 2015-07-15 13:00 +0200
Re: [RFC PATCH v2] memory-barriers: remove smp_mb__after_unlock_lock() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-07-15 15:20 +0200
Re: [RFC PATCH v2] memory-barriers: remove smp_mb__after_unlock_lock() Michael Ellerman <mpe@ellerman.id.au> - 2015-07-15 05:10 +0200
Re: [RFC PATCH v2] memory-barriers: remove smp_mb__after_unlock_lock() Will Deacon <will.deacon@arm.com> - 2015-07-15 12:50 +0200
Re: [RFC PATCH v2] memory-barriers: remove smp_mb__after_unlock_lock() Michael Ellerman <mpe@ellerman.id.au> - 2015-07-16 04:10 +0200
Re: [RFC PATCH v2] memory-barriers: remove smp_mb__after_unlock_lock() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-07-16 17:20 +0200
Re: [RFC PATCH v2] memory-barriers: remove smp_mb__after_unlock_lock() Benjamin Herrenschmidt <benh@kernel.crashing.org> - 2015-07-17 01:00 +0200
Re: [RFC PATCH v2] memory-barriers: remove smp_mb__after_unlock_lock() Will Deacon <will.deacon@arm.com> - 2015-07-17 11:40 +0200
Re: [RFC PATCH v2] memory-barriers: remove smp_mb__after_unlock_lock() Peter Zijlstra <peterz@infradead.org> - 2015-07-17 12:20 +0200
Re: [RFC PATCH v2] memory-barriers: remove smp_mb__after_unlock_lock() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-07-17 14:50 +0200
Re: [RFC PATCH v2] memory-barriers: remove smp_mb__after_unlock_lock() Benjamin Herrenschmidt <benh@kernel.crashing.org> - 2015-07-18 00:20 +0200
Re: [RFC PATCH v2] memory-barriers: remove smp_mb__after_unlock_lock() Will Deacon <will.deacon@arm.com> - 2015-07-20 15:40 +0200
Re: [RFC PATCH v2] memory-barriers: remove smp_mb__after_unlock_lock() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-07-20 15:50 +0200
Re: [RFC PATCH v2] memory-barriers: remove smp_mb__after_unlock_lock() Will Deacon <will.deacon@arm.com> - 2015-07-20 16:00 +0200
Re: [RFC PATCH v2] memory-barriers: remove smp_mb__after_unlock_lock() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-07-15 16:20 +0200
Re: [RFC PATCH v2] memory-barriers: remove smp_mb__after_unlock_lock() Michael Ellerman <mpe@ellerman.id.au> - 2015-07-16 03:40 +0200
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